The present invention relates to a plastic molded support member for aligning a rotatable shaft and a process for manufacturing same and more particularly for an integrated lower cowl/plenum support member formed of molded plastic for directly mounting a wiper drive motor and rotatable wiper arm drive shafts.
A typical windshield wiper drive module is shown and described in FIG. 2 of U.S. Pat. No. 5,946,763. The disclosed windshield wiper system conventionally includes a so-called tubular frame that carries the two wiper drive shafts and a motor carrying plate on which the wiper motor is fastened. The wiper drive shafts of the system are able to carry out a rotational pendulum motion via a linkage that is driven by the motor. An electrical plug connection serves for triggering the wiper motor via corresponding control elements, i.e., a steering column switch, a rain sensor, or the like. The windshield wiper system conventionally requires a tubular frame system with four fastening points at which the windshield wiper system is fastened to the motor vehicle body by means of screws. These fastening points are simultaneously used for connecting the windshield wiper system and the receptacle into a cowl plenum module. Consequently, the cowl plenum module is provided with through-openings of corresponding shape at the locations of the fastening points. The cowl plenum module is conventionally provided with two additional through-openings in order to insert the free ends of the wiper drive shafts from below the cowl plenum module. The windshield wiper system and the cowl plenum module are connected into an assembly at the fastening points by means of corresponding screws. The tubular frame system supporting the windshield wiper motor, wiper drive shafts, and connecting linkages conventionally provides the structural rigidity and mounting orientation of the wiper drive shafts in the desired configuration with respect to the wiper motor and the tubular frame is directly connected to the motor vehicle body to maintain the desired orientation. The cowl plenum module conventionally provided no orientation function or critical support function for the windshield wiper motor, drive shafts, and linkage assembly.
It would be desirable in the present invention to provide an integral cowl/plenum and wiper drive assembly, where the cowl/plenum structure completely replaces the separate tubular support structure previously required for the wiper drive assembly. It would be desirable in the present invention to mount the wiper drive motor directly to plastic bosses formed integral with the cowl/plenum structure to eliminate the conventional requirement of separate rubber grommets used for isolation mounting of the wiper drive motor and the tubular frame structure previously required. It would be desirable in the present invention to provide the cowl/plenum structure with a water management area allowing the wiper motor drive mounting area to be enclosed and maintained in a separate dry area. It would be desirable in the present invention to simplify connection of the water drainage tube to the cowl/plenum structure by moving the mounting surface from a blind view surface to a visible mounting surface, and/or reducing the three attachment points previously used to only two attachment points, and/or providing a locating lip on the cowl/plenum structure to locate the drain tube during the fastening operation. It would be desirable in the present invention to provide a motor harness attachment integral with the cowl/plenum structure. It would be desirable in the present invention to provide an air filter receptacle integral with the cowl plenum structure. It would be desirable to provide an integral security sensor bracket with the cowl/plenum structure. It would be desirable to provide the cowl/plenum structure with sufficient rigidity to prevent sagging of the plastic cowl/plenum structure over time and over a range of anticipated temperature exposure in order to support a hood seal in sealing engagement with the lower surface of a hood in a closed position. It would be desirable to provide a cowl plenum structure formed of a thermoplastic injection molded material, where the thermoplastic injection molded material is 45% glass filled. It would be desirable to provide the cowl/plenum structure with sufficient rigidity to withstand all wiper system functional loads/forces created during operation. It would be desirable in the present invention to optionally mount sound deadening material to the integral cowl/plenum structure to reduce airborne noise from the engine compartment migrating into the passenger compartment. It would be desirable in the present invention to provide integral pivot bosses with the cowl/plenum structure for receiving pressed in bearings for aligning the windshield wiper drive shafts with respect to the cowl/plenum structure.
An apparatus according to the present invention provides an integral cowl/plenum structure for supporting a wiper drive motor, linkage, and wiper arm drive shafts without the need for a separate tubular support frame extending between the wiper drive motor and wiper arm drive shafts as is conventional. The present invention reduces the weight of the conventional plenum and wiper drive motor assembly. The present invention also reduces the cost of the assembly, and reduces the number of parts associated with the assembly. The integral cowl/plenum structure according to the present invention permits mounting the wiper drive motor directly to plastic bosses formed integral with the cowl/plenum structure. The cowl/plenum structure includes integral bosses for receiving the wiper arm drive shafts extending therethrough. The integral drive shaft bosses provide proper orientation of the rotational axes of the wiper drive shafts with respect to the windshield to be cleaned. The proper orientation of the wiper arm shafts is provided by press fitting bearings in opposite ends of the integral wiper arm drive shaft bosses to provide the proper orientation of the rotational axis of the wiper arm drive shaft. In the preferred process of manufacturing the integral cowl/plenum structure according to the present invention, the plastic molded integral structure is placed in a bearing mounting fixture while cooling where alignment shafts extend through the integral wiper arm drive shaft bosses for guiding the bearings during insertion into the opposing ends of the bosses while maintaining the desired orientation of the rotational axis as the integral cowl/plenum structural part continues to cool.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.